This invention relates to cordless electrical kettles.
Conventional cordless kettles have a power base unit to be connected to a power supply and a base extension unit connected to the kettle, the base unit and extension unit each including an electrical connector, with the connectors arranged to electrically interconnect when the kettle is placed on the base unit. In a preferred form the interface between the two units is circular to allow the units to be connected to each other at any angle about the vertical axis of the units. To achieve proper connection one of the connectors fits into a circular sectioned cylindrical recess in the other of the connectors, conventionally the base unit has an upstanding connector fitting into a recess in the connector of the kettle extension unit. It is a requirement that the two connectors are in firm end to end contact.
Such a kettle has a lever-type ON/OFF switch, the actuator of which can be moved to an ON connecting position to complete the electrical circuit when the units are connected, and which will be automatically moved to the OFF position when the water in the kettle boils.
In addition, in a preferred embodiment, in order to prevent arcing between the connectors if the kettle is lifted while the circuit is completed, a biasing means is provided which biases the switch to an OFF position if the kettle is lifted and before the contactors cease to make electrical contact. The biasing means acts on a downwardly extending plunger within the socket recess, the plunger being coupled to an operating arm which interacts with the ON/OFF switch lever. Depression of the plunger as a result of a firm connection of the connectors removes the biasing from the ON/OFF switch lever so that it can stay in the ON position. The plunger is necessarily spaced radially to one side of the vertical axis of the units. Space constrictions on conventional kettles of this type means that the vertical movement of the plunger between its operative and inoperative conditions is small, not exceeding about 1 mm.
The base unit and the extension unit are both conventionally molded from plastics materials and the connectors securely fastened thereto so that no vertical movement of the connectors relative to the moldings can occur. Because of the tolerances which must be allowed for in the molding. manufacture and because of warping of the moldings, it is the practice, in order to ensure proper firm contact in every product between the connectors (and the depression of the plunger), that the units are designed to allow a small gap between the surfaces of the moldings surrounding the connectors, when the connectors are interconnected. A gap of 0.5 to 1 mm is usually built into the design.
However this gap leads to vibration/wobble of the kettle in use which is undesirable. An object of the present invention is to prevent/reduce the amount of vibration or wobble in a cordless kettle of this type.
Conventionally the base of the extension unit is formed with three equal feet having rounded lower surfaces and it is these lower surfaces which form engagement parts and are, by design, spaced from the upper surface of the base molding.